Prior art pumping and switching devices for liquids are typically very complicated, take up significant space and are very heavy. These devices are used extensively for pumping liquids such as hydraulic oil or similar fluid between a supply tank and a load, such as a hydraulically operated mechanism, for example, a piston and cylinder. Moreover, when a filtering capability of the liquid is added to the pumping and switching devices, a further complication is provided to the overall system, which also increases the space the system occupies.